From the International Lake Superior Board of Control and U.S. Army Corps of Engineers:
The monthly mean water level of Lake Superior in December was 183.60 m (602.36 ft). This is 21 cm (8 in) above the long-term (1918-2013) December average and the highest December level since 1996.
For the eleventh consecutive month, the net water supplies to Lake Superior were above average again in December.
The level of Lake Superior declined 6 cm (2 in) last month, while on average the lake declines 8 cm (3 in) in December. The Lake Superior level at the beginning-of-January is 24 cm (9 in) above average, 27 cm (11 in) above the level recorded a year ago at this time, and 40 cm (16 in) above its chart datum level.
The monthly mean water level of Lake Michigan-Huron in December was 176.53 m (579.16 ft). This is 21 cm (8 in) above the long-term (1918-2013) December average, the highest December level since 1997.
For the fifth consecutive month, the net water supplies to Lake Michigan-Huron were also above average in December. The level of Lake Michigan-Huron remained at about the same level as last month, while on average the lake declines by 4 cm (2 in) in December. The level of Lake Michigan-Huron is 24 cm (9 in) above its long-term average beginning-of-January level, 58 cm (23 in) higher than it was a year ago, and 54 cm (21 in) above its chart datum level.
The levels of both Lakes Superior and Michigan-Huron are expected to decline in January.